Large Magnetic Moments of Arsenic-Doped Mn Clusters and their Relevance to Mn-Doped III-V Semiconductor Ferromagnetism

Abstract

We report electronic and magnetic structure of arsenic-doped manganese clusters from density-functional theory using generalized gradient approximation for the exchange-correlation energy. We find that arsenic stabilizes manganese clusters, though the ferromagnetic coupling between Mn atoms are found only in Mn${}_2$As and Mn${}_4$As clusters with magnetic moments 9 ${\mu }_B$ and 17 ${\mu }_B$, respectively. For all other sizes, $x=$ 3, 5-10, Mn${}_x$As clusters show ferrimagnetic coupling. It is suggested that, if grown during the low temperature MBE, the giant magnetic moments due to ferromagnetic coupling in Mn${}_2$As and Mn${}_4$As clusters could play a role on the ferromagnetism and on the variation observed in the Curie temperature of Mn-doped III-V semiconductors.

4 Pages, 3 Figures[1 EPS and 2 JPG files], RevTeX4